1. Field of the Invention
This invention is generally directed to pendulum type devices and is more particularly directed to pendulum type horological devices and more particularly still to a horological device wherein a pendulum is used to indicate the time or to partially indicate the time.
2. Description of the Prior Art
It is well known that the oscillations of the so-called gravity pendulum, as opposed to a torsion pendulum, has a period dependent upon the length (l) of the suspension of the pendulum bob and the acceleration of a freely falling body (g) due to gravity in accordance with the well known equation: ##EQU1##
Since acceleration in a gravity field is the same for all objects, disregarding air resistance and the like, all pendulums having the same suspension length will swing with the same harmonic motion along a vertically oriented curved path, i.e. with the same simple periodic motion, and, if started together with small amplitude, single pendulums of different masses will swing in synchronism. It was Huggins who in the seventeenth century first adapted the pendulum to regulate a mechanism for keeping time and thereby originated the first accurate clock mechanism. The use of a pendulum, therefore, as a time keeping device is of fairly ancient vintage. One well known example is the use of a pendulum in a grandfather's clock. In the grandfather's clock the pendulum is used not only to regulate the clock mechanism, but is also used as a decorative feature, the regular movement of which is interesting to the observer. With the arrival of modern technology the pendulum has no longer been as useful as a time keeping mechanism. However, its popularity as a decorative feature has continued and dummy pendulums having no time regulating or horological function have continued to be used in clocks. In such clocks the pendulum merely mimics the normal utilitarian function of a pendulum while providing an eye attracting movement as a decorative feature of the horological device. Exemplary disclosures of such devices may be found in the following U.S. patents.
U.S. Pat. No. 2,722,097 issued Nov. 1, 1955 to J. Lefrand discloses a conical pendulum alternating current clock wherein the pendulum motion both drives and regulates the clock mechanism. In the Lefrand device the clock is controlled by the frequency of a pendulum formed of electrically conductive material and caused to swing in a conical path by means of a rotating or oscillating electric field, as in an induction motor.
U.S. Pat. No. 2,995,005 issued Aug. 8, 1961 to R. L. Boyles describes a swinging pendulum clock, "the pendulum motion of which is utilized for other than timekeeping purposes and does not control the operation of the clock mechanism."
U.S. Pat. No. 3,762,154 issued Oct. 2, 1973 to C. Petrides is directed to a simulated pendulum clock wherein the "pendulum is functionally separated from a timekeeping movement for driving the hands of the clock."
U.S. Pat. No. 3,762,155 issued Oct. 2, 1973 to C. B. Marble is also directed to a pendulum clock wherein the pendulum is functionally separated from the timekeeping movement which drives the hands of the clock. The '155 patent is particularly directed to a pendulum arm with an upper pendulum drive arm having a permanent magnet positioned adjacent to an electromagnetic movement for driving the pendulum and a lower pendulum arm removably connected to the upper pendulum arm.
U.S. Pat. No. 3,903,684 issued Sept. 9, 1975 to A. Wilson discloses a pendulum type time or interval keeper in which the swing of a pendulum per se indicates elapsed periods of time. The pendulum includes a magnetic means which interacts with a second magnetic means mounted on the base in a keeper. The magnetic means is not used for adding energization to the swings of the pendulum or determining the position to which the pendulum swings, but serves instead to operate the keeper at the conclusion of movement.
U.S. Pat. No. 3,924,401 issued Dec. 9, 1975 to E. Heim discloses the provision of a dummy torsion pendulum (as opposed to an oscillating pendulum) under a clock mechanism.
U.S. Pat. No. 4,121,416 issued Oct. 24, 1978 to C. Niemczyk discloses a dummy oscillating pendulum periodically energized by solenoid coil means energized momentarily during the pendulum oscillations by contact switch means.
U.S. Pat. No. 4,203,282 issued May 20, 1980 to B. Radzun is broadly similar to the dummy torsion arrangement shown in U.S. Pat. No. 3,924,401 to Heim described above.
U.S. Pat. No. 4,468,132 issued Aug. 28, 1984 to N. Nakamura discloses a swinging body clock in which oscillation of the body of the clock as well as an attached pendulum is effected by magnetic means hidden within or behind the clock case.
While the above described devices have provided a varied repertory of clock type devices in which a pendulum is used other than as a time regulating means, but is used instead as an attention attracting or decorative device, none makes use of the pendulum as a time indicating device as contrasted with a time regulating or time measuring device.
It is an object of the invention, therefore, to provide a unique and attractive timekeeping device utilizing a pendulum.
It is a further object of this invention to provide a timekeeping device wherein a pendulum functions as a time indicator means.
It is another object of this invention to provide a timekeeping device which is driven either electrically or mechanically and incorporates a pendulum as at least part of the time indicating means.
It is a still further object of this invention to provide a timekeeping or horological device in which a pendulum serves as a novel and attractive time indicating means.
Other objects and features of the device will be evident from the following description and illustrations of the invention.